JP2010196641A - High pressure fuel pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce lateral force acting on a plunger 2 when the plunger 2 guided by a cylinder 1 is driven by a cam 10 through a lifter 5 guided by a lifter guide 4. <P>SOLUTION: The lifter 5 is divided to a capped tube shape guide body 6 guided by the lifter guide 4 and abutting on the plunger 2, and a drive body 7 fitted in the tube part 6a of the guide body 6, abutting on the cap part 6b of the guide body 6 at one end part and including a roller 9 abutting on the cam 10 at another end part. When inclination of the guide body 6 due to guide clearance Cg is defined as θg and inclination of the plunger 2 due to plunger clearance Cp is defined as θp, the clearances Cg, Cp are set to satisfy a relation θg≤θp. A clearance Cd for establishing line contact of the roller 9 and the cam 10 is secured between the guide body 6 and the drive body 7. An abutment part of the guide body 6 and the drive body 7 are formed in a spherical shape and lubricating oil is supplied to the abutment part from an oil hole 14. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a high-pressure fuel pump used for a direct injection internal combustion engine or the like.

  A conventional high-pressure fuel pump is, as is known from Patent Document 1, etc., a lifter that is fitted in a cylinder so as to be reciprocally slidable, and a lifter guide that is reciprocally slidable in the same direction as the plunger. By being driven by the cam through the plunger, the volume of the pump chamber is changed by the plunger to perform the suction / discharge operation.

JP 2001-295754 A

  By the way, when a roller lifter is used as the lifter, that is, when the roller is rotatably held by the lifter and brought into contact with the cam, the roller and the cam must always be in line contact.

  For this purpose, the guide clearance of the lifter (clearance between the lifter guide and the lifter) is increased so that the lifter can operate following the cam surface.

  However, in the roller lifter, the contact surface pressure between the roller and the cam is high, and when misalignment occurs, the surface pressure becomes abnormally high due to the roller tilting and the cam contacting the edge, and the contact between the roller and the cam. Abnormal wear such as pitching may occur on the surface, which may reduce reliability.

  If the guide clearance of the lifter (clearance between the lifter guide and the lifter) is further increased, the contact between the roller and the cam can be maintained normally, but the lifter is tilted too much and an excessive lateral force is applied to the plunger. This may cause abnormalities such as worst seizure.

  In view of such a situation, an object of the present invention is to reduce the lateral force applied to the plunger while maintaining normal contact between the roller and the cam when the roller lifter is used.

  In order to solve the above problems, in the present invention, the lifter is inserted into the lifter guide so as to be slidable in a reciprocating manner and is in contact with the plunger, and is inserted into the cylindrical portion of the guide body. One end is in contact with the lid of the guide body, and the other end is divided into a drive body that rotatably holds a roller that contacts the cam.

  Further, when θg is the inclination of the guide body due to the clearance between the lifter guide and the guide body, and θp is the inclination of the plunger due to the clearance between the cylinder and the plunger, these are set so that θg ≦ θp. Set clearance.

  In addition, a clearance is secured between the guide body and the driving body so that the roller and the cam can come into line contact. In addition, at least one of the contact portions between the guide body and the driving body is formed into a spherical shape, and the lubricating oil is supplied to the contact portion.

  According to the present invention, the lifter drive body can be tilted sufficiently to maintain normal contact between the roller and the cam, while the lifter guide body is restrained from tilting to the plunger. Such lateral force can be reduced and the plunger can be operated stably.

Sectional drawing of the principal part of the high-pressure fuel pump which shows one Embodiment of this invention Sectional drawing of the principal part of the high-pressure fuel pump which shows other embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail.

  FIG. 1 is a cross-sectional view of a main part of a high-pressure fuel pump showing an embodiment of the present invention.

  This high pressure fuel pump is a plunger pump used to supply high pressure fuel to the fuel injection valve in a direct injection internal combustion engine having a fuel injection valve that directly injects fuel into the combustion chamber.

  A plunger 2 is fitted into the cylinder 1 so as to be slidable back and forth, and the volume of the pump chamber 3 is changed by the plunger 2 to perform suction and discharge operations.

  More specifically, the volume of the pump chamber 3 is changed by reciprocating sliding of the plunger 2, and the intake side one-way valve (see FIG. 5) from the fuel intake passage (low pressure fuel pump side; not shown) in the intake stroke in which the plunger 2 descends. The fuel is sucked into the pump 3 chamber through a discharge stroke in which the plunger 2 rises, and the fuel in the pump chamber 3 is supplied to the fuel injection valve through a discharge-side one-way valve (not shown). Discharge to a discharge passage (not shown).

  For the suction side one-way valve, a solenoid (not shown) that can keep the suction side one-way valve open regardless of the pressure in the pump chamber 3 by electromagnetic force generated by energization. And the solenoid is energized until an arbitrary timing of the discharge stroke of the plunger 2, the suction side one-way valve is held in an open state, and the suction side one-way valve is opened after the solenoid is energized. The discharge operation is started by closing the valve, and the discharge amount of the plunger 2 is controlled by controlling the closing timing of the one-way valve on the suction side by controlling the energization end timing of the solenoid. Yes.

  The plunger 2 is driven by a cam 10 via a lifter 5 fitted in the lifter guide 4 so as to be reciprocally slidable in the same direction as the plunger 2.

  The lifter 5 is divided into a guide body 6 and a drive body 7.

  The guide body 6 has a cylindrical shape with a lid, and the outer periphery of the cylindrical portion 6a is fitted into the lifter guide 4 so as to be slidable back and forth. The outer end surface of the lid portion 6 b is in contact with the base end portion of the plunger 2.

  The driving body 7 has a columnar shape and is slidably fitted into the cylindrical portion 6 a of the guide body 6, and one end portion (upper end portion) is formed on the inner end surface of the lid portion 6 b in the cylindrical portion 6 a of the guiding body 6. It comes to contact.

  Here, the inner end surface of the lid portion 6b in the cylindrical portion 6a of the guide body 6 forms a concave spherical surface 6c, and one end portion of the driving body 7 that contacts the spherical surface 6a forms a convex spherical surface 7a. The spherical surface 7a has a smaller radius of curvature and is in point contact at the center. However, the curvature may be the same and spherical contact may be made.

  A roller 9 is rotatably held by a pin 8 at the other end (lower end) of the driving body 7, and this roller 9 is in contact with the cam 10 in a line contact state.

  Further, the driving body 7 is provided with a pin 11 for preventing rotation from a side exposed from the cylindrical portion 6 a of the guide body 6, and is provided in a guide groove 12 provided in the lifter guide 4 in the axial direction. Rushed. Thereby, the drive body 7 is prevented from rotating.

  The cam 10 is formed on the camshaft of the engine side by side with a cam for driving the intake / exhaust valve. Two cam noses are formed on the outer cam surface so that the plunger reciprocates twice by one rotation of the camshaft. They are formed at intervals of 180 °.

  Therefore, when the cam nose pushes up the drive body 7 of the lifter 5 through the roller 9 by the rotation of the cam 10, the guide body 6 is further pushed up, thereby pushing up the plunger 2 and the discharge stroke is started. Further, when the cam nose is separated from the roller 9 by further rotation of the cam 10, the guide body 6 and the drive body 7 are pushed back by a return spring (not shown), and at the same time, the plunger 2 is lowered, Become.

  In addition, there is a large amount of lubricating oil used to lubricate each part around such a high-pressure fuel pump. In particular, because of the lubrication of the sliding surface between the lifter guide 4 and the guide body 6 of the lifter 5, the lifter An annular lubricating oil groove 13 is formed on the inner peripheral surface of the guide 4.

  Also, the lid 6b of the guide body 6 is provided with an oil hole 14 obliquely avoiding the contact surface with the plunger 2, and through this oil hole 14, the contact portion between the guide body 6 and the drive body 7 ( Lubricating oil is supplied between the spherical surfaces 6c and 7a.

  Here, the inclination of the guide body 6 due to the clearance (guide clearance) Cg between the lifter guide 4 and the guide body 6 is θg, and the inclination of the plunger 2 due to the clearance between the cylinder 1 and the plunger 2 (plunger clearance) Cp. These clearances Cg and Cp are set so that θg ≦ θp when θp is satisfied. In practice, the guide clearance Cg is made smaller than the plunger clearance Cp.

  Further, a clearance (drive unit clearance) Cd is secured between the guide body 6 and the drive body 7 so that the roller 9 and the cam 10 can come into line contact.

  The relationship between the three clearances will be described. The inclination of the guide body 6 by the clearance (guide clearance) Cg between the lifter guide 4 and the guide body 6 is θg, and the clearance between the cylinder 1 and the plunger 2 (plunger clearance). ) When θp is the inclination of the plunger 2 due to Cp and θd is the inclination of the drive body 7 due to the clearance between the guide body 6 and the drive body 7 (drive section clearance) Cd, so that θg ≦ θp ≦ θd These clearances Cg, Cp, Cd are set.

  In this way, the lifter 5 is divided into the guide body 6 and the drive body 7, and the drive body 7 can be tilted sufficiently with respect to the swing by the cam 10. Contact can be kept normal. Therefore, it is possible to avoid occurrence of abnormal wear such as pitching on the contact surface between the roller 9 and the cam 10, and to improve reliability and durability.

  Further, at least one of the abutting portions of the guide body 6 and the driving body 7 is formed in a spherical shape, and lubricating oil is supplied to the abutting portion, whereby the movement of the driving body 7 swung by the cam 10 is performed. Can prevent the guide body 6 from being affected as much as possible.

  On the other hand, with respect to the guide body 6, by reducing the guide clearance Cg and suppressing the inclination, more specifically, by suppressing the inclination of the guide body 6 to be equal to or less than the inclination of the plunger 2, lateral force (external force) applied to the plunger 2 is reduced. , And durability can be improved. Of course, seizure can be prevented.

  Further, if the lifter 5 (guide body 6) is greatly inclined, the hitting sound when contacting the lifter guide 4 is increased and the merchantability is lowered, but the inclination of the lifter 5 (guide body 6) can be suppressed. Further, the hitting sound between the lifter 5 (guide body 6) and the lifter guide 4 can be suppressed, and the merchantability can be improved.

  Next, another embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the same element as embodiment of FIG. 1, description is abbreviate | omitted, and a different element is demonstrated.

  In the present embodiment, the inner end surface (spherical surface 6c) of the lid portion 6b in the cylindrical portion 6a of the guide body 6 of the lifter 5 and one end portion (spherical surface 7a) of the driving unit 7 fitted into the cylindrical portion 6a. In the meantime, an oil reservoir 21 is formed.

  An annular groove is formed on the outer periphery of the drive body 7 so that the lubricating oil is secured in the oil reservoir 21, and an oil seal 22 is attached to the annular groove so that the inner peripheral surface of the cylindrical portion 6 a of the guide body 6. Adhere to.

  Further, the lid 6b of the guide body 6 is provided with an oil hole 23 at the center thereof, and lubricating oil is introduced from the oil hole 23 into the oil reservoir 21 when the guide body 6 is moved downward, and when the guide body 6 is moved upward. The oil hole 23 is closed by the plunger 2 so that the lubricating oil is prevented from flowing out.

  Thus, the oil reservoir 21 is provided between the guide body 6 and the drive body 7 of the lifter 5, and the oil reservoir 21 is configured such that the guide body 6 and the drive body 7 are in contact with each other via the oil reservoir 21. Becomes a cushion material, and the peak fuel pressure in the pump chamber 3 can be reduced by reducing the speed at which the plunger 2 boosts the fuel. Thereby, the contact pressure between the roller 9 and the cam 10 can be kept low and stabilized at a predetermined pressure or lower.

DESCRIPTION OF SYMBOLS 1 Cylinder 2 Plunger 3 Pump chamber 4 Lifter guide 5 Lifter 6 Guide body 6a Tube part 6b Cover part 6c Spherical surface 7 Drive body 7a Spherical surface 8 Pin 9 Roller 10 Cam 11 Anti-rotation pin 12 Guide groove 13 Lubricant oil groove 14 Oil hole 21 Oil reservoir 22 Oil seal 23 Oil hole

Claims (2)

The plunger inserted into the cylinder so as to be slidable in a reciprocating manner is driven by a cam via a lifter inserted into the lifter guide so as to be slidable in the same direction as the plunger. In high-pressure fuel pumps that change and perform suction and discharge operations,
The lifter is inserted into the lifter guide so as to be slidable in a reciprocating manner, and a covered cylindrical guide body that is in contact with the plunger, and is inserted into the cylindrical portion of the guide body, and one end of the guide comes into contact with the lid portion of the guide body. And a drive body that rotatably holds a roller that contacts the cam at the other end,
When the inclination of the guide body due to the clearance between the lifter guide and the guide body is θg, and the inclination of the plunger due to the clearance between the cylinder and the plunger is θp, θg ≦ θp Set these clearances,
A clearance is secured between the guide body and the driving body so that the roller and the cam can be in line contact,
A high-pressure fuel pump characterized in that at least one of the abutting portions between the guide body and the driving body is formed in a spherical shape and lubricating oil is supplied to the abutting portion.   2. The high-pressure fuel pump according to claim 1, wherein an oil reservoir is provided between the guide body and the drive body, and the guide body and the drive body are in contact with each other via the oil reservoir.

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